\begin{tikzpicture}[every node/.style={fill=white, inner sep=1pt}]
    \draw [line width=1.5pt] (0, 0) node [draw, inner sep=1.5em] {$a^b = N$};
    \draw [line width=1.5pt] (5, 0) node [draw, inner sep=1.5em] {$\log_{a}{N} = b$};

    \draw (-0.5, -0.3) -- (-0.5, -1.5) -- (4.7, -1.5) -- (4.7, -0.3);
    \draw (2.3, -1.5) node {底数};

    \draw (-0.3, 0.3) -- (-0.3, 1.6) -- (5.8, 1.6) -- (5.8, 0.3);
    \draw (2.3, 1.6) node {指数 \quad 对数};

    \draw (0.4, 0.3) -- (0.4, 1.1) -- (5.1, 1.1) -- (5.1, 0.3);
    \draw (2.45, 1.1) node {幂 \quad 真数};

    \draw [dashed] (2.3, 2.0) -- (2.3, 0.5);
\end{tikzpicture}

